Optimization of heat treatment of magnetic materials applying the thermomagnetic curves data

1. Introduction To produce modern magnetic materials the rapid cooling from the melt is used very often. The as-prepared material is in an amorphous or microcrystalline form and its optimal properties can be reached after a specific heat treatment. This process results in irreversible changes in the structure and orientation. As a typical example, there are the nanocrystalline materials gained by controlled crystallization from original iron-or nickel-based amorphous alloys using various techniques. During their subsequent heat treatment, only limited changes in the material structure are admitted. Usually they include some stress relief and building of fine crystalline structure or precipitation, but almost in no cases phase transformations, grain coarsening or recrystallisation. For finding the critical temperatures and classification of these processes, thermomagnetic curves can be used [1, 2]. Examples of thermomagnetic curves are presented in Figs. 1 and 2 for two different materials.